This invention relates in general to solar energy collectors and in particular to such collectors which are designed as modular, air-to-air units.
The field of solar energy heating is currently quite active, although many facets of the technology are actually in their infancy. New developments and discoveries are occurring quite rapidly and these often cause earlier theories to be abandoned and new approaches to be explored. The fundamental concepts involved with solar radiation absorption and subsequent heat transfer are in a very general sense easy to understand. For example, a black body type of surface is capable of absorbing incident solar radiation more readily than is a white surface. Similarly, the rate of heat transfer from one medium to another depends in part on the temperature difference which is present between the two mediums. However, while these concepts are easy to understand, there are an even greater number of factors whose effect both singularly and in combination with other parameters is not easily determined. Consider such factors as collector plate size, material and coating, also the flow rate and composition of the working fluid, the positional orientation of the collector relative to incident solar radiation, and the manner of utilization of the working fluid for subsequent heating. Although with time and experimentation, a particular combination of factors could be arranged in a single collector which might be an optimal design, at least as to those particular factors, there are still further constraints which must be considered. These constraints include the cost, mounting location requirements, mounting space availability, the suitability of the device for domestic as well as commercial use, the producibility and the reliability and maintainability of the device.
The following listed patents disclose solar energy concepts which have been conceived, presumably in an effort to provide an improvement over the prior art in existence at the time of their conception.
______________________________________ Patent No. Patentee Issue Date ______________________________________ 991,161 McHenry 5/02/11 2,680,437 Miller 6/08/54 3,902,474 Pyle 9/02/75 3,987,786 Keyes et al. 10/26/76 3,995,615 Hojnowski 12/07/76 4,018,211 Barr 4/19/77 4,020,989 Kautz 5/03/77 4,029,080 Warren 6/14/77 4,038,969 Smith 8/02/77 4,046,133 Cook 9/06/77 ______________________________________
McHenry discloses a solar heat motor wherein a solar collector having a series of offset, upright panels is employed for absorption of heat and heat transfer to a circulating medium. The panels defined a tortuous path across the collector surface.
Miller discloses a solar heat trap wherein a solar collector is arranged within an enclosure and the collector includes a plurality of offset plates which define a series of pathways through the heat trap and across the surface of the plates.
Pyle discloses a solar heat converter which includes a box with a maze of air passageways which are partially filled with shredded heat-conductive material.
Keyes et al. discloses self-contained apparatus for collecting, storing and transmitting solar heat. The collector unit is provided with a series of baffles to expose conditioning air to the heat-collecting surfaces as the air follows a tortuous path through the apparatus.
Honjnowski discloses a solar heat collector panel which includes amolded plastic base with longitudinally extending channels. A flat metal heat-absorbing plate is disposed just below the cover and a corrugated plate is welded to the underside of the heat-absorbing plate to define fluid passageways.
Barr discloses an arrangement for solar energy collection and transfer wherein a honeycombed panel assembly includes a heat-transfer multi-celled honeycomb layer and a plurality of lateral fluid passageways formed in the cell walls for guiding and passing heat transfer fluid.
Kautz discloses a light-transmitting building panel wherein upper and lower corrugated sheets are laterally offset relative to a central sheet so as to define a plurality of passageways between the various corrugations and each face of the central sheet.
Warren discloses a thermal collector of solar energy for installation in the roof structure of a building. The collector includes a thermally conductive backing which carries an energy-absorbing material through a plurality of passageways. The backing is also arranged as one side of an air-flow passageway for heat transfer from the backing to a circulating flow of air.
Smith discloses a solar energy collector with an energy absorbing structure wherein a plurality of open-ended cells are arranged in a honeycomb style and a tortuous air flow path is provided in and out through the cells for absorbing and carrying away the energy collected by the cells.
Cook discloses a solar panel assembly which includes a heat-absorptive panel and a series of covering panels which permit the passage of light. A single flow passageway is disposed across one surface of the heat-absorptive panel and the opposite, back surface of this panel is thermally insulated.
Unfortunately, what each of these references disclose, with the exception of Miller, is either a relatively complicated collector design involving a significant number of component pieces and the need for somewhat precise fabrication techniques or a relatively complicated system often employing liquid as a heat-transfer medium. Although the performance of such collectors and systems may be suitable for their intended purpose, when the incorporation of such collectors and systems into a particular structure involves significant construction and/or modifications to that structure, then the versatility of the device is lost and the cost may not be affordable. Due to the wide range of heating demands which can be supplemented by the use of solar energy, what is needed is a portable, modular unit which can easily and inexpensively be adapted to various structures for a variety of heating demands. Equally important is that such a device be inexpensive to manufacture and provide a relatively basic construction style. While the device of Miller does appear to provide an inexpensive, portable, air-to-air unit, this device incorporates a plurality of flow paths and a limited amount of surface area for solar radiation absorption. The device utilizes glass plates for heat storage and although glass does not lose heat by radiation, the heat-storage capacity of glass is less than that of aluminum for the same mass and thus the overall solar radiation heat absorption and heat capacity of the device, relative to its weight, is limited. Furthermore, glass acts somewhat as an insulator and will not conduct heat throughout its surface as readily as would aluminum, and this reduces the rate of uniform heat distribution throughout the heat-transfer surfaces. These various drawbacks reduce the efficiency of such a unit in that incident solar radiation will not be rapidly conducted throughout the surfaces across which the working medium passes and this reduces the heat transfer to the working medium and consequently limits the ability of the collector surface to absorb additional solar radiation.